Tools required: Torx 5 screwdriver, Phillips size 0 screwdriver
First remove the battery cover and battery. Remove the four screws you see.
Your phone will now look like the picture below.
You can now remove what is effectively the front cover of the phone. It is held on with double sided tape which may need replacing. You'll now have access to the PCB (printed circuit board). Please note that the F3 has a paper screen and this cannot be replaced wihout great difficulty.